Image projection devices are well known and have been used for many years. Such systems typically rely upon an image modulator and an optical projection means to project the image upon a diffuse screen, whereon it is viewed by an observer. Image modulators were originally hard copy media based, for example, films such as transparencies and motion picture film. More recently, soft copy projectors have become available and are based upon, for example micro electromechanical systems or liquid crystal devices as well as laser projection systems, for example see U.S. patent application 2003/0039036 A1 by Kruschwitz et al., published Feb. 27, 2003. In any case, the image modulator creates an image plane which is projected through an optical system upon a screen as is commonly seen, for example, in a cinema or in digital computer monitor projector. Image projection devices are also employed in head mounted displays.
The optical systems used with image projectors typically include some combination of lenses with a focus control, and often a zoom control. These controls allow the projector to project a focused image upon the screen at a variety of distances and with a variety of displayed image sizes. However, such systems are encumbered by the weight and size of the projection optical system and are restricted to imaging upon a single screen.
U.S. Pat. No. 6,170,953 B1 issued Jan. 9, 2001 to Lee et al. describes a laser video projector for projecting an image to a plurality of screens. However, this system relies upon extensive beam combining optics to integrate the light paths and project image at a plurality of screens.
There is a need therefore for an alternative image projection system that avoids these limitations.